Amalgam is a combination of metals that has been the most popular and effective filling material used in dentistry for the last 150 years. Although it sometimes is called “silver amalgam,” amalgam actually consists of a combination of metals. These include silver, mercury, tin and copper. Small amounts of zinc, indium or palladium also may be used. However, its popularity as restorative material is decreasing nowadays due to concerns about unfavorable health effects and environmental pollution. Researchers agree that amalgam restorations leach mercury into the mouth, but consistent findings are not available to report whether it has any significant health risk. The American Society of Dental Surgeons (ASDS) in the year 1843, declared use of amalgam to be malpractice because of the fear of mercury poisoning in patients. In 1859, the American Dental Association (ADA) was founded and it did not forbid use of amalgam. The ADA position on the safety of amalgam has remained consistent since its foundation. In 1920s inferences were made that mercury was not tightly bound in amalgam so its use was discouraged. In this review, we will show the convincing evidences pointed out to adverse health effects due to dental amalgam restorations.